MSC Therapy for Osteoarthritis: An Unfinished Story.

Mesenchymal stromal cells (MSCs) have firmly occupied the attention of orthopedic clinicians and scientists for most of the last 25 years. Hundreds of laboratories worldwide have carried out research aimed at unraveling the biological characteristics of these cells and probing the manner in which they potentially contribute to cartilage and bone repair. Clinical trials registries indicate that they are also being tested in patient studies for a wide range of conditions such as osteoarthritis, rheumatoid arthritis, fracture repair, regeneration of articular cartilage, tendon repair, and for treatment of degenerative disc disease. Despite these efforts, the effectiveness of MSCs as a treatment modality for these conditions is still uncertain and market authorizations have been limited. In addition, critical and clear phenotypic parameters for defining MSCs are uncertain and a coherent biological framework surrounding the therapeutic mechanism of action is not yet available. Added to this, cell manufacturing protocols are complex and costly and present substantial challenges in terms of regulatory oversight and standardization. Despite these obstacles, MSCs still remain at the forefront of efforts in Regenerative Medicine, based on a conviction that this technology can provide an effective treatment paradigm for major diseases where there is still an unmet need.